frame matching issue

I'm working on a pilot show and one of the assistant editors has stumbled across an interesting issue and we're trying to figure out how to fix it.

So when the assistant editor group the sub clips by scene and then do frame match, it references to the master clip instead of the sub clip. This issue occurs on certain scenes and other scenes will match back to the sub clip fine. It does not seem to have any consistency throughout the footage and happens randomly.

Now our speculation is that the avid software the assistant editor is using might be buggy and might have to re install avid media composer. But even if it is we're trying to figure out how to frame match the footage referencing to the master clips to reference to the sub clips. If you guys know of any solution please let me know. Thanks you!